1. Field of the Invention
The present invention relates to a method for producing a layered piezoelectric element provided in an ink jet print head which ejects ink droplets to produce diagrams or characters by dots on a print medium.
2. Description of the Related Art
Piezoelectric elements for generating a displacement upon application of a voltage can obtain a large displacement amount when provided in a layered form with piezoelectric material and internal electrodes provided in alternation.
Japanese Patent Application (Kokai) No. HEI-6-79871 discloses a configuration typical for an ink jet print head. As shown in FIG. 1, vertically-displacing pillar-shaped piezoelectric ceramic elements 81 serving as layered actuators are formed from a block-shaped sintered body into which elongated grooves have been opened with a slicer or other instrument. The piezoelectric ceramic elements 81 are configured from stacks of thin piezoelectric element sheets alternating with thin internal electrodes. This configuration allows low voltage drive of the piezoelectric ceramic elements 81. The internal electrodes are exposed in alternation at opposing side surfaces of the piezoelectric ceramic elements 81. The internal electrodes are connected, by wire bonding or by other means, to a drive power source for supplying a voltage for driving the piezoelectric ceramic elements 81.
An elastic thin plate 82 is adhered to the tip ends of the pillar-shaped piezoelectric ceramic elements 81. Further, a nozzle plate 84 made from resin and formed with ink channels 83 and nozzles 83a is adhered to the thin plate 82 so that tip ends of the piezoelectric ceramic elements 81 are positioned over corresponding ink channels 83. Application of a voltage to the piezoelectric ceramic elements 81 produces displacement which deforms the thin plate 82 and ejects ink in the ink channel 83 from the nozzles 83a. Dot-pattern characters and other images can therefore be printed.
However, the pillar-shaped piezoelectric ceramic elements 81 of the ink jet print head shown in FIG. 1 are easily placed under a stress while slicing the narrow grooves that separate them. Therefore, the pillar-shaped piezoelectric ceramic elements 81 can easily snap or break so that production yield of the ink jet print head is low.
Also, the ink jet print head is unreliable because the pillar-shaped piezoelectric ceramic elements 81 can easily break when driven.
Also, only straight grooves can be formed using a slicer, which places limits to the shapes in which the pillar-shaped piezoelectric ceramic elements 81 can be formed.
Also, a slicer can only form one groove at a time. Therefore, forming a large number of pillar-shaped piezoelectric ceramic elements 81 is time consuming and troublesome.